1. Field of the Invention
The present invention relates to a method for performing a removal process on a dielectric film, and more particularly to a method for removing damaged material within a feature in a bilayer film on a substrate following an etching, ashing or wet cleaning process.
2. Description of Related Art
As is known to those in the semiconductor art, interconnect delay is a major limiting factor in the drive to improve the speed and performance of integrated circuits (IC). One way to minimize interconnect delay is to reduce interconnect capacitance by using low dielectric constant (low-k) materials during production of the IC. Such low-k materials have also proven useful for low temperature processing. Thus, in recent years, low-k materials have been developed to replace relatively high dielectric constant insulating materials, such as silicon dioxide. In particular, low-k films are being utilized for inter-level and intra-level dielectric layers between metal layers of semiconductor devices. Additionally, in order to further reduce the dielectric constant of insulating materials, material films are formed with pores, i.e., porous low-k dielectric films. Such low-k films can be deposited by a spin-on dielectric (SOD) method similar to the application of photo-resist, or by chemical vapor deposition (CVD). Thus, the use of low-k materials is readily adaptable to existing semiconductor manufacturing processes.
While low-k materials are promising for fabrication of semiconductor circuits, the present inventors have recognized that these films also provide many challenges. First, low-k films tend to be less robust than more traditional dielectric layers and can be damaged during wafer processing, such as by etch and plasma ashing processes generally used in patterning the dielectric layer. Further, some low-k films tend to be highly reactive when damaged, particularly after patterning, thereby allowing the low-k material to absorb water and/or react with other vapors and/or process contaminants that can alter the electrical properties of the dielectric layer. These challenges may be an impediment to use of low-k films in some device applications.